When installing a television receiving antenna, the common practice is to orient the antenna such that a field strength meter connected thereto has a maximum deflection or reading. However, such a meter may show a good acceptable signal level when, in fact, the signal is unacceptable because of the presence of interference signals therein. The most common interference signals encountered in television are caused by reflections of the television signal itself. If the reflective signal is of sufficient strength, it results in a second image displaced on the screen a short distance from the normal image. These displaced images have come to be known as ghosts and the reflected signals which cause them are known in the art as ghost signals or ghosts. While ghosts are most common in urban areas where tall buildings are commonplace, they may even occur in rural areas as a result, for example, of reflections from water towers. Ghosts are also caused by reflections on the lead-in cable or distribution cables in cable TV systems.
In order to facilitate the installation of television antennas it would be desirable to incorporate in a field strength meter a circuit for detecting ghosts or other interference signals in the received television signal and also to indicate the strength of such interference signals. The service technician could thus aim the antenna in the best possible direction without multiple trips between the antenna and the television receiver and without the need of an assistant.